1. Field of the Invention
The invention relates to a flange connection for pipes, in particular, air pipes.
2. Description of the Related Art
The pipe systems for air are usually configured in many variations of pipes, often in the form of a folded spiral-seam pipes, of individual lengths determined by constructional conditions and of industrially pre-manufactured parts such as branch pipes, curved sections, transition sections between pipes of different diameters, and functional components such as shut-off flaps, throttle flaps, or volume flow regulators.
The required tightness of the corresponding connections demands precisely manufactured, high-quality pipes and parts. Even though, the assembly expenditure is proportionally a high component of the manufacturing costs.
In order to reduce the assembly work, plug connections have been developed, for example, as disclosed in EP 0 596 230 B1, that can be easily manipulated. A pipe section to be inserted into a pipe end is provided with a sealing ring of foamed material of, for example, 10 to 20 Shore hardness. When the pipe section is inserted, the sealing ring rolls from a mounting seat into a sealing seat, is compressed accordingly, and provides a sealing action.
The plug connection, however, requires a high working expenditure in the case of a retrofitting assembly because it requires an axial displacement of the pipes and parts.
The demounting and insertion of individual parts is simpler in the case of flange connections which, after detachment of the fastening means, allow a simple removal of the part in the transverse direction of the pipeline. However, flange connections entail the problem that during the first installation the pipe ends, especially the pipe ends of the individually installed pipes, must be provided with flanges. Pre-manufactured end pieces with flanges for a clamping insertion into the pipe ends are known, but have not found acceptance in practice.
It is an object of the present invention to provide a connection which overall is more assembly-friendly.
In accordance with the present invention, this is achieved in that a pipe section provided with a flange is embodied as a plug connection with a sealing ring which, during insertion into a pipe end, rolls from the mounting seat into the sealing seat.
For this purpose, the invention is based on a flange connection and provides that a pipe section provided with a flange is embodied as a plug connection with a sealing ring that rolls from a mounting seat into a sealing seat when the plug connection is inserted into the pipe end.
Accordingly, the connection is embodied twofold, i.e., as a flange connection as well as a plug connection. The initial mounting is thus significantly simplified in comparison to the previously employed simple flange connections. A retrofit mounting is possible in the aforementioned simple way that is made possible by the flange connection. This is especially advantageous for installing and removing of functional components for the now prescribed cleaning of pipe systems in certain time intervals by means of cleaning robots moved through the pipes.
Expediently, the flange has an essentially known configuration of a profiled sheet metal such that the flange widens from the outer edge radially inwardly to a step so that it can be connected with a counter flange of the same configuration by means of a clamping device in the form of a clamping bracket having a matching cross-section.
However, as a new configuration of the connection it is suggested according to the invention to use the aforementioned steps of the flanges for connecting, in a simpler way, clamps instead of the clamping bracket, wherein the clamps engage with their preferably eye-shaped ends like a hook under the two steps and preferably have a lateral projection in the form of a lever handle at one of its eye-shaped ends.
Furthermore, in the connection of simplifying assembly and ensuring a seal-tight connection, it is provided that the flanges have a circumferential groove, respectively, in their contact surfaces provided on their end faces and that a sealing ring is positioned in the two grooves facing one another. In one embodiment, the sealing ring is connected to one of the flanges. According to another embodiment, the sealing ring can also be comprised of two halves each connected to one of the flanges, respectively, wherein each half projects with a curved portion slightly from the groove past the contact surface.
In order to be able to employ the invention also for pipe diameters that are larger, especially above 300 mm up to 1000 mm or more, it is proposed according to the invention that the first sealing ring is comprised of a hose whose material has a hardness of more than 30 Shore.
The reason for this measure is explained in the following:
The sealing rings of the plug connection have, in addition to the sealing function, also an axial connecting function since they secure the inserted pipes and pipe parts in the axial direction against the axial forces caused by the pressure of the medium. The securing force, resulting from the pressing of the sealing ring against the pipe wall and from its frictional connection on the pipe wall, and the intrinsic resistance force of the sealing ring against rolling back are proportional to the length of the sealing ring and increase thus linearly with its diameter, while the axial force resulting from the pressure of the medium increases by the second power. The maximum possible pressing force and stiffness of the sealing ring and thus the resistance force against (back) rolling, relative to the unit of length, finally are no longer sufficient to generate the required retaining force. They are limited by the force to be exerted for performing the flex work required for rolling the sealing ring during the insertion of the plug connection member into the pipe end, and this force increases in any case linearly with the diameter even for a pressing force and stiffness that remain the same.
For the same pressing force against the pipe wall, the hose according to the invention, which has in its center a hollow space, rolls more easily along the pipe wall than the cellular rubber or similar closed-cell foamed materials that have been used for the sealing ring in the past, which however otherwise completely fill the cross-sectional area of the sealing ring with foamed material, i.e.,, there is no central hollow space as in the hose. After locking in the sealing seat, however, the sealing ring according to the invention resists a return movement to a much greater degree than the foam. The hose wall, which in itself is comprised of a stiffer material, forms between its support on the pipe wall by friction and a direct support against one of the sidewalls of the sealing seat formed as a groove a stiffer supporting element, acting mechanically at a slant and with a substantial component in the axial direction, than the corresponding cross-sectional portion of the foamed material can provide. The solid material (not foamed, no cells) of the hose wall is also more reliable than the more or less inhomogeneous foamed material.
Suitable parameter combinations for achieving the aforementioned effects can be determined by routine tests.
The material of the hose should expediently have a hardness of 40 to 70 Shore, preferably 50 to 60, Shore.
The wall thickness of the hose should be, in general, dimensioned suitably when it is 20 to 25% of the hose diameter.
The sealing seat is preferably embodied as a groove formed in the pipe section with preferably a flat bottom and with a sidewall across which the sealing ring rolls during insertion into the pipe end. The height of the sidewall is 25 to 30% of the height of the compressed sealing ring.
The other sidewall of the groove which, preferably, together with the first sidewall, surrounds and contacts the sealing ring, is higher than the first sidewall, preferably approximately twice as high.
Expediently, the sealing ring is compressed in the sealing seat to a height of 55 to 70%, preferably 60 to 65%, of its original diameter.
The aforementioned surrounding (embracing) of the sealing ring by the sidewalls contacting it contributes significantly to the stabilization of the sealing ring in its compressed form in the sealing seat.
The mounting seat of the sealing ring is preferably defined by a groove with a curved bottom, wherein the diameter of the pipe section, beginning at this groove increases to the edge of the first sidewall of the groove forming the sealing seat. The bottom of the groove forming the sealing seat is positioned at a greater diameter of the pipe section than the bottom of the other groove forming the mounting seat. dr
In the drawing:
FIG. 1 is a detail of the pipeline with a flange connection according to the invention shown in axial section;
FIG. 2 shows on an enlarged scale a detail of a pipe section with sealing ring in the mounting position and in the sealing position;
FIG. 3 shows a detail of a further embodiment of the clamping device connecting the flanges;
FIG. 4.shows a detail of yet another embodiment of the clamping device connecting the flanges; and
FIG. 5 illustrates the assembly process of the two flanges with a two-part sealing ring; and
FIG. 6 illustrates the assembly process for the two flanges with a single-part sealing ring.